diff --git a/beacon_node/beacon_chain/src/lib.rs b/beacon_node/beacon_chain/src/lib.rs
index 5fa7e7a77..48a42b941 100644
--- a/beacon_node/beacon_chain/src/lib.rs
+++ b/beacon_node/beacon_chain/src/lib.rs
@@ -8,6 +8,7 @@ pub mod test_utils;
 pub use self::beacon_chain::{BeaconChain, BlockProcessingOutcome, InvalidBlock, ValidBlock};
 pub use self::checkpoint::CheckPoint;
 pub use self::errors::BeaconChainError;
+pub use attestation_aggregator::Outcome as AggregationOutcome;
 pub use db;
 pub use fork_choice;
 pub use parking_lot;
diff --git a/beacon_node/eth2-libp2p/src/rpc/methods.rs b/beacon_node/eth2-libp2p/src/rpc/methods.rs
index 85ef7e06f..47e47f3eb 100644
--- a/beacon_node/eth2-libp2p/src/rpc/methods.rs
+++ b/beacon_node/eth2-libp2p/src/rpc/methods.rs
@@ -1,7 +1,7 @@
 use ssz::{Decodable, DecodeError, Encodable, SszStream};
 /// Available RPC methods types and ids.
 use ssz_derive::{Decode, Encode};
-use types::{BeaconBlockBody, BeaconBlockHeader, Epoch, Hash256, Slot};
+use types::{Attestation, BeaconBlockBody, BeaconBlockHeader, Epoch, Hash256, Slot};
 
 #[derive(Debug)]
 /// Available Serenity Libp2p RPC methods
@@ -97,6 +97,12 @@ impl RPCResponse {
     }
 }
 
+#[derive(Debug, Clone)]
+pub enum IncomingGossip {
+    Block(BlockGossip),
+    Attestation(AttestationGossip),
+}
+
 /* Request/Response data structures for RPC methods */
 
 /// The HELLO request/response handshake message.
@@ -236,3 +242,15 @@ pub struct BeaconChainStateResponse {
     /// The values corresponding the to the requested tree hashes.
     pub values: bool, //TBD - stubbed with encodeable bool
 }
+
+/// Gossipsub message providing notification of a new block.
+#[derive(Encode, Decode, Clone, Debug, PartialEq)]
+pub struct BlockGossip {
+    pub root: BlockRootSlot,
+}
+
+/// Gossipsub message providing notification of a new attestation.
+#[derive(Encode, Decode, Clone, Debug, PartialEq)]
+pub struct AttestationGossip {
+    pub attestation: Attestation,
+}
diff --git a/beacon_node/eth2-libp2p/src/rpc/mod.rs b/beacon_node/eth2-libp2p/src/rpc/mod.rs
index a1573ec93..925c36616 100644
--- a/beacon_node/eth2-libp2p/src/rpc/mod.rs
+++ b/beacon_node/eth2-libp2p/src/rpc/mod.rs
@@ -11,7 +11,7 @@ use libp2p::core::swarm::{
     ConnectedPoint, NetworkBehaviour, NetworkBehaviourAction, PollParameters,
 };
 use libp2p::{Multiaddr, PeerId};
-pub use methods::{HelloMessage, RPCMethod, RPCRequest, RPCResponse};
+pub use methods::{HelloMessage, IncomingGossip, RPCMethod, RPCRequest, RPCResponse};
 pub use protocol::{RPCEvent, RPCProtocol};
 use slog::o;
 use std::marker::PhantomData;
diff --git a/beacon_node/network/src/beacon_chain.rs b/beacon_node/network/src/beacon_chain.rs
index cc54e8ae0..26cea0065 100644
--- a/beacon_node/network/src/beacon_chain.rs
+++ b/beacon_node/network/src/beacon_chain.rs
@@ -5,10 +5,10 @@ use beacon_chain::{
     parking_lot::RwLockReadGuard,
     slot_clock::SlotClock,
     types::{BeaconState, ChainSpec},
-    CheckPoint,
+    AggregationOutcome, CheckPoint,
 };
 use eth2_libp2p::HelloMessage;
-use types::{BeaconBlock, BeaconBlockBody, BeaconBlockHeader, Epoch, Hash256, Slot};
+use types::{Attestation, BeaconBlock, BeaconBlockBody, BeaconBlockHeader, Epoch, Hash256, Slot};
 
 pub use beacon_chain::{BeaconChainError, BlockProcessingOutcome};
 
@@ -37,6 +37,11 @@ pub trait BeaconChain: Send + Sync {
     fn process_block(&self, block: BeaconBlock)
         -> Result<BlockProcessingOutcome, BeaconChainError>;
 
+    fn process_attestation(
+        &self,
+        attestation: Attestation,
+    ) -> Result<AggregationOutcome, BeaconChainError>;
+
     fn get_block_roots(
         &self,
         start_slot: Slot,
@@ -119,6 +124,18 @@ where
         self.process_block(block)
     }
 
+    fn process_attestation(
+        &self,
+        _attestation: Attestation,
+    ) -> Result<AggregationOutcome, BeaconChainError> {
+        // Awaiting a proper operations pool before we can import attestations.
+        //
+        // Returning a useless error for now.
+        //
+        // https://github.com/sigp/lighthouse/issues/281
+        return Err(BeaconChainError::DBInconsistent("CANNOT PROCESS".into()));
+    }
+
     fn get_block_roots(
         &self,
         start_slot: Slot,
diff --git a/beacon_node/network/src/message_handler.rs b/beacon_node/network/src/message_handler.rs
index 57923b2c3..a788e83c9 100644
--- a/beacon_node/network/src/message_handler.rs
+++ b/beacon_node/network/src/message_handler.rs
@@ -4,7 +4,7 @@ use crate::service::{NetworkMessage, OutgoingMessage};
 use crate::sync::SimpleSync;
 use crossbeam_channel::{unbounded as channel, Sender};
 use eth2_libp2p::{
-    rpc::{RPCRequest, RPCResponse},
+    rpc::{IncomingGossip, RPCRequest, RPCResponse},
     PeerId, RPCEvent,
 };
 use futures::future;
@@ -39,8 +39,8 @@ pub enum HandlerMessage {
     PeerDisconnected(PeerId),
     /// An RPC response/request has been received.
     RPC(PeerId, RPCEvent),
-    /// A block has been imported.
-    BlockImported(), //TODO: This comes from pub-sub - decide its contents
+    /// A gossip message has been received.
+    IncomingGossip(PeerId, IncomingGossip),
 }
 
 impl MessageHandler {
@@ -90,6 +90,10 @@ impl MessageHandler {
             HandlerMessage::RPC(peer_id, rpc_event) => {
                 self.handle_rpc_message(peer_id, rpc_event);
             }
+            // we have received an RPC message request/response
+            HandlerMessage::IncomingGossip(peer_id, gossip) => {
+                self.handle_gossip(peer_id, gossip);
+            }
             //TODO: Handle all messages
             _ => {}
         }
@@ -186,6 +190,19 @@ impl MessageHandler {
             }
         };
     }
+
+    /// Handle RPC messages
+    fn handle_gossip(&mut self, peer_id: PeerId, gossip_message: IncomingGossip) {
+        match gossip_message {
+            IncomingGossip::Block(message) => {
+                self.sync
+                    .on_block_gossip(peer_id, message, &mut self.network_context)
+            }
+            IncomingGossip::Attestation(message) => {
+                //
+            }
+        }
+    }
 }
 
 pub struct NetworkContext {
diff --git a/beacon_node/network/src/sync/import_queue.rs b/beacon_node/network/src/sync/import_queue.rs
index 6508af89e..17cbd2f12 100644
--- a/beacon_node/network/src/sync/import_queue.rs
+++ b/beacon_node/network/src/sync/import_queue.rs
@@ -104,7 +104,7 @@ impl ImportQueue {
     }
 
     /// Returns `true` if `self.chain` has not yet processed this block.
-    fn is_new_block(&self, block_root: &Hash256) -> bool {
+    pub fn is_new_block(&self, block_root: &Hash256) -> bool {
         self.chain
             .is_new_block_root(&block_root)
             .unwrap_or_else(|_| {
diff --git a/beacon_node/network/src/sync/simple_sync.rs b/beacon_node/network/src/sync/simple_sync.rs
index 4ee349043..06ccbafd3 100644
--- a/beacon_node/network/src/sync/simple_sync.rs
+++ b/beacon_node/network/src/sync/simple_sync.rs
@@ -204,6 +204,8 @@ impl SimpleSync {
             self.known_peers.insert(peer_id.clone(), remote);
         }
 
+        // TODO: boot peer if finalization is wrong.
+
         match remote_status {
             PeerStatus::OnDifferentChain => {
                 info!(
@@ -462,6 +464,62 @@ impl SimpleSync {
         self.process_import_queue(network);
     }
 
+    /// Process a gossip message declaring a new block.
+    pub fn on_block_gossip(
+        &mut self,
+        peer_id: PeerId,
+        msg: BlockGossip,
+        network: &mut NetworkContext,
+    ) {
+        debug!(
+            self.log,
+            "BlockGossip";
+            "peer" => format!("{:?}", peer_id),
+        );
+        // TODO: filter out messages that a prior to the finalized slot.
+        //
+        // TODO: if the block is a few more slots ahead, try to get all block roots from then until
+        // now.
+        //
+        // Note: only requests the new block -- will fail if we don't have its parents.
+        if self.import_queue.is_new_block(&msg.root.block_root) {
+            self.request_block_headers(
+                peer_id,
+                BeaconBlockHeadersRequest {
+                    start_root: msg.root.block_root,
+                    start_slot: msg.root.slot,
+                    max_headers: 1,
+                    skip_slots: 0,
+                },
+                network,
+            )
+        }
+    }
+
+    /// Process a gossip message declaring a new attestation.
+    ///
+    /// Not currently implemented.
+    pub fn on_attestation_gossip(
+        &mut self,
+        peer_id: PeerId,
+        msg: AttestationGossip,
+        _network: &mut NetworkContext,
+    ) {
+        debug!(
+            self.log,
+            "AttestationGossip";
+            "peer" => format!("{:?}", peer_id),
+        );
+
+        // Awaiting a proper operations pool before we can import attestations.
+        //
+        // https://github.com/sigp/lighthouse/issues/281
+        match self.chain.process_attestation(msg.attestation) {
+            Ok(_) => panic!("Impossible, method not implemented."),
+            Err(_) => error!(self.log, "Attestation processing not implemented!"),
+        }
+    }
+
     /// Iterate through the `import_queue` and process any complete blocks.
     ///
     /// If a block is successfully processed it is removed from the queue, otherwise it remains in